JPH06103712A - External force correcting method in disk device - Google Patents

Abstract

PURPOSE:To suppress a seek error due to the external force correcting error by sampling the temperature with a prescribed cycle and timely correcting the external force to the rapid temperature variation. CONSTITUTION:The temperature variation in a magnetic disk device is detected by a temperature sensor 11 with the prescribed sampling cycle, and when the temperature variation higher than the prescribed temperature is generated against the reference temperature of a holding circuit 12, an interruption is generated in an MPU 14 and also the holding circuit 12 is reset to hold the temperature as the next reference temperature. By the MPU 14, the external force at the temperature at the time when a target cylinder is moved, is measured over again, then the correction amount for the purpose of correcting the external force is obtained and settled as a new servo constant which makes a voice coil current corresponding to the positional error to zero. Thereby, the external force is timely corrected corresponding also to the rapid temperature variation, and the settling time of the seek for the external force correcting error is reduced, then the seeking error is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a correction method when a magnetic head of a magnetic disk device controlled by a microprocessor (MPU) is moved to a predetermined cylinder (track) of a disk for positioning. Especially,
The present invention relates to a method of correcting an external force generated by a flexible printed circuit (FPC), which is a transmission line for sending a signal from a head to a read / write circuit, by a temperature change.

In recent years, the capacity of magnetic disk devices has been increased, and the track pitch has been reduced accordingly. As a result, the rate at which the external force from the flexible printed circuit (FPC) that constitutes the transmission path for sending signals from the head to the read / write circuit influences the positioning of the head, increases The positioning accuracy becomes more severe, and the ratio of the eccentricity of the rotating medium and the deviation between the heads is apparently increasing, and it is required to improve the accuracy of the conventional correction.

[0003]

2. Description of the Related Art FIG. 5 is a diagram for explaining an external force value in a magnetic disk device, FIGS. 6 and 7 are diagrams for explaining a conventional external force correction method, and FIG. 6 is a block diagram.
FIG. 7 is a flowchart showing a conventional correction method, and FIG. 8 is a diagram showing an example of measuring a cylinder position and an external force.

In the disk device 1 shown in FIG. 5, a magnetic head 15 is attached to the tip of a head arm 17 controlled by a voice coil motor (VCM) 16 with respect to a medium rotated by a spindle motor. The magnetic head
A flexible printed circuit (FPC) 18 is used to transfer the read and write signals between 15 and the external read and write circuits.

The flexible printed circuit (FPC) 18 is formed, for example, by forming a transmission circuit with a copper foil on a resin material such as polyimide and then covering the resin material with polyimide or the like.

Here, when the magnetic head 15 moves from the inner side to the outer side, the flexible printed circuit (FP
C) The bend of 18 becomes large, and the flexible printed circuit
A reaction force is generated by the (FPC) 18, and the reaction force depends on the environmental temperature in the magnetic disk device.

Also, there is an external force due to the grease of the bearing of the voice coil motor (VCM) 16 or "wind" generated by the rotation of the medium. A conventional correction method for such an external force will be described with reference to FIGS.

Normally, when a seek command is generated in a host device (not shown), for example, a channel processing device, the microprocessor of the magnetic disk device concerned.
The (MPU) 14 calculates the difference between the current position of the magnetic head 15 and the magnetic head position (specifically, the track number) designated by the seek command, and calculates the voice consisting of the acceleration current and the deceleration current. The coil motor control current is sent to the voice coil motor (VCM) 16 via the digital / analog converter (D / A) 140, and the magnetic head arm 17
Is rotated to a predetermined position, and when the position information of the magnetic head arm 17 and the track position designated by the seek command match, the voice coil motor control current becomes "0", and the balance state is reached. Becomes

At this time, the magnetic head arm is actually
Since a reaction force is generated in the flexible printed circuit (FPC) 18, a correction current (Bia
s) is sent to the voice coil motor (VCM) 16 based on a servo constant described later.

Since the correction current has temperature dependency as described above, conventionally, the external force was measured by the method shown in the flowchart of FIG. 7 to generate the servo constant. That is, triggered by a timer interrupt from a real-time timer provided in the microprocessor (MPU) 14 of the magnetic disk device 1,
The processing shown in the flowchart of FIG. 7 is executed.

First, when a timer interrupt occurs, the number of the target cylinder is set to, for example, "0", and the target cylinder 0 is sought and positioned (on-track). In the on-track state here, the position error (the error between the center position of the track number designated by the seek command executed by the microprocessor and the actual position of the magnetic head) is "0", so it is ideal. The voice coil motor control current value should be "0".
However, in reality, as described above, some force (external force) is working, and in order to balance the magnetic head at a predetermined position, a correction current for canceling it is applied to the voice coil motor (VCM). It is necessary to send to 16.

As described above, the current flowing through the voice coil motor (VCM) 16 when the position error is "0" is the current value (bias) for canceling the external force applied to the magnetic head arm 17 at the cylinder position at that time. Value).

The current for canceling this (voice coil motor control current value) is measured at the measurement point shown in FIG. 6 and stored in a RAM (not shown) inside the microprocessor (MPU) 14. {Processing step 100 in FIG. 7
When the measurement of the external force at the target cylinder 0 is completed, the target cylinder number is
Regarding the number of the target cylinder with "α" added,
The measurement of the external force is repeated until the final cylinder to obtain the servo constant at that time. {Refer to processing steps 103 to 106 in Fig. 7} Fig. 8 shows an example of measuring the external force at each cylinder position measured as described above. As the head moves from the inner to the outer, the external force is nonlinear. Increase to.

Therefore, when a seek command is issued from the host device in this state, the external force correction value corresponding to the cylinder number designated by the seek command is calculated from the servo constants, and the calculated current value is calculated. By flowing it through the voice coil motor (VCM) 16, the magnetic head arm 17 was made to equilibrate with the external force at a predetermined position.

[0015]

As described above, in the conventional external force correction method, the external force value is measured at regular intervals, and the value is stored as a servo constant in a table on a main memory (not shown). When the seek command is issued from the host device, the servo constant is referred to,
The external force value of the magnetic head arm 17 is canceled by obtaining and adding the external force correction value corresponding to the cylinder position designated by the seek command.

Therefore, in the conventional external force correction method, the external force is measured and fetched as a correction value at regular time intervals.
The correction value is not updated until the next timer interrupt occurs and a new external force measurement is performed.

Therefore, if there is a rapid temperature change before the next measurement time, the settling time of the seek operation (accelerating and decelerating currents for the seek operation, and after seeking near the desired cylinder, There is a problem that the time until the position of the magnetic head is accurately determined: see FIG. 6) extends or a seek error occurs.

Incidentally, as a conventional technique for correction when positioning the magnetic head arm at a predetermined position, Japanese Patent Laid-Open No. 63-209077 has been proposed.
There is a publication "Magnetic disk device", JP-A-63-291274, "Magnetic disk device", and JP-A-2-9066 "Magnetic disk device". However, it does not correct the external force generated from the flexible printed circuit (FPC) or the like which the applicant of the present application has described as the above-mentioned prior art, and does not solve the above problems.

In view of the above-mentioned conventional drawbacks, the present invention provides, for example,
This is a correction method for positioning (on-track) by moving the magnetic head of a magnetic disk device controlled by a microprocessor (MPU) to a specified cylinder (track) of the disk, and especially reading from the head and writing. The flexible printed circuit (FPC), which is a transmission line for sending signals to the circuit, compensates for the temperature change of the external force generated, and it is possible to reduce the seek settling time and seek error due to the error of the external force correction value. The purpose is to provide a possible method.

[0020]

FIG. 1 is a block diagram showing the principle of the present invention. The above problems can be solved by the external force correcting method in the disk device configured as follows.

(1) An external force correction method for positioning the magnetic head of the disk device 1 controlled by the microprocessor 14 by moving the magnetic head to a predetermined cylinder position of the disk, which is provided in the disk device 1. When the difference between the temperature held by the temperature sensor 11 held and the temperature sampled at a constant cycle becomes equal to or more than a predetermined ± x degree C, an interrupt is generated to the microprocessor 14 and an interrupt is generated. Microprocessor 14
Then, the correction amount for the required external force at each cylinder position is measured again, and the servo constant for the external force is recreated.

(2) An external force correction method for positioning the magnetic head of the disk device 1 controlled by the microprocessor 14 by moving the magnetic head to a predetermined cylinder position of the disk, which is provided in the disk device 1. When the difference between the held temperature value from the temperature sensor 11 and the temperature sampled at a constant cycle exceeds a predetermined ± x degree, an interrupt is generated to the microprocessor 14 and the interrupt is generated. Microprocessor 14
Then, referring to the external force change table for a predetermined temperature change at each preset temperature, the temperature difference ± x degrees detected by the temperature sensor 11 at the temperature at which this interrupt was generated The external force correction amount for C is calculated, and the servo constants at the previous correction are added or subtracted to correct the servo constants.

[0023]

That is, in the present invention, for example, a temperature sensor is installed in a magnetic disk device controlled by a microprocessor (MPU), and a temperature change in the magnetic disk device is sampled at a predetermined sampling cycle. Then, when a temperature change of more than ± x ° C is detected with respect to the reference temperature held by the hold circuit, an interrupt is generated to the microprocessor (MPU) and the hold circuit is reset. Then, the temperature at the time of generating the interrupt is held in the hold circuit as the next reference temperature.

Then, in the microprocessor (MPU),
When the interrupt is detected, the external force at the temperature when the target cylinder is moved from the inner side to the outer side, for example, is measured again to obtain a new servo constant.

Alternatively, in the microprocessor (MPU), when the interrupt is detected, the temperature indicated by the temperature sensor is read, and the external force change table set in advance corresponding to each temperature is referred to A correction amount for correcting an external force corresponding to the detected temperature difference at temperature is obtained, and the servo constant at the previous correction is added / subtracted to rewrite the servo constant.

Therefore, the voice coil motor control current value (digital value) for correcting the external force in a timely manner with respect to a sudden temperature change can be obtained, and the external force correction error caused in the valley between the correction and the correction can be obtained. This has the effect of suppressing the settling time of seek and phenomena such as seek error.

[0027]

Embodiments of the present invention will be described in detail below with reference to the drawings. The above-mentioned FIG. 1 is a principle configuration diagram of the present invention, and FIG.
FIG. 4 is a diagram showing an embodiment of the present invention, FIG. 2 is a flow chart showing the external force correction method according to the present invention, and FIG. 3 is a time chart showing the operation of the window comparator.
FIG. 4 shows an example of changing the external force correction table (servo constant) due to temperature change.

In the present invention, for example, in the magnetic disk device 1 controlled by the microprocessor (MPU) 14,
The temperature sensor 11 is attached, the temperature change in the magnetic disk device 1 is sampled and taken out at a predetermined sampling cycle, and the reference temperature held by the hold circuit 12 is not less than ± x degrees C. When a temperature change is detected, the microprocessor (MPU) 14 is interrupted, the hold circuit 12 is reset, and the temperature at the time of the interrupt is set to the hold circuit 12 as the next reference temperature. Hold. Then, in the microprocessor (MPU) 14, when the interrupt is detected, the target cylinder is moved from the inner side to the outer side, for example, the external force at the temperature is measured again, and a new servo constant is obtained. Or, the microprocessor (MPU) 14 reads the temperature indicated by the temperature sensor 11 when the interrupt is detected, and
By referring to the external force change table set corresponding to each temperature, the correction amount for correcting the external force corresponding to the detected temperature difference at that temperature is obtained, and the servo constant at the time of the previous correction Means for adding / subtracting to and rewriting the servo constant is a means necessary for implementing the present invention. still,
The same reference numerals denote the same objects throughout the drawings.

The external force correcting method in the disk device of the present invention will be described below with reference to FIGS. In the present embodiment, a magnetic disk device will be described as an example, but the present invention is not limited to this, and an optical disk device, a magneto-optical disk device, a disk device, etc.
It goes without saying that the present invention can be applied to any device as long as the device seeks on the medium and the head is on-track on a predetermined track to perform the read / write operation.

First, referring to the time chart of FIG. 3, a method of detecting a sudden temperature change in the window comparator 13 in FIG. 1 will be described. The temperature information output from the temperature sensor 11 provided in the magnetic disk device 1 is sampled at a predetermined sampling cycle, and the temperature information of the hold circuit 12 that holds the temperature at which the interrupt was generated before, The current sampled temperature is compared with the window comparator 13, and when it is detected that there is a change of a predetermined temperature change ± x degrees C or more (see the time chart of FIG. 3), the microprocessor (MPU) 14 is notified. Generate an interrupt.

Microprocessor that recognizes the interrupt
The (MPU) 14 executes the processing shown in the flow charts of FIGS. 2 (a) and 2 (b), updates the servo constants in response to the rapid temperature change causing the interrupt, and Guarantees the operation by the seek instruction.

FIG. 2A shows an example in which the servo constant is measured again. First, the window comparator 13
Then, a sudden temperature change (± x
(Change in C) (see FIG. 3) is detected, an interrupt (external interrupt) is generated in the microprocessor (MPU) 14.

Microprocessor recognizing the interrupt
In the (MPU) 14, for example, the inner cylinder 0 is set as the target cylinder and the seek operation is performed on the target cylinder 0.

In the seek operation, as described above, an acceleration current and a deceleration current for causing the head to seek the target cylinder 0 are flown, and when the vicinity of the target cylinder 0 is reached, a so-called settling operation is started, and the head Servo control is performed so that the voice coil current corresponding to the position error (position error) corresponding to the difference between the position information from 15 and the position information with the target cylinder 0 becomes "0", and the correction for external force is performed. Voice coil motor control current (Bias) flows to perform.

Then, the digital value corresponding to the voice coil motor control current (Bias) at the time when the voice coil current corresponding to the position error becomes "0",
It is read as an external force at the measurement point in FIG. 1 and used as the servo constant for the cylinder 0. {Refer to the processing steps 110 to 112 of FIG. 2 (a)} When the measurement of the external force at the target cylinder 0 is completed, the target cylinder number obtained by adding “α” to the target cylinder number is as described above. Similarly, the measurement of the external force is repeated until the final cylinder, and the servo constant corresponding to each cylinder at that time is obtained. {Processing steps 113 to 11 of FIG. 2 (a)
Therefore, when a seek command is issued from the host device in this state, the external force correction value corresponding to the cylinder number indicated by the seek command in the current operating environment is obtained from the servo constants, By flowing the obtained current value to the voice coil motor (VCM) 16, the magnetic head arm 17 can be balanced with an external force at a predetermined position.

Next, referring to the flow chart of FIG. 2B, the external force change table of the servo constants at respective temperatures provided in the main memory (not shown) of the microprocessor (MPU) 14 is referred to in advance. Then, a method of rewriting the servo constant at the temperature when the interrupt occurs will be described.

In the microprocessor (MPU) 14,
When the interrupt is recognized, the current temperature is read from the temperature sensor 11, the external force change table is referred to, and the temperature and the sudden temperature difference that caused the interrupt are read.
Find the amount of change in external force in each cylinder that corresponds to the difference from the previous rewrite value.

Then, in the servo constant rewritten last time,
The amount of change is added or subtracted, and the servo constant in each cylinder is rewritten according to the temperature at which the interrupt occurs and the temperature difference, and the servo constant corresponding to the sudden temperature change is obtained. {Refer to processing steps 120 to 123 in FIG. 2B} FIG. 4 shows an example of changing the external force correction table (servo constant) due to temperature change.

In FIG. 4, the external force value shown by the solid line represents the servo constant rewritten last time, and the external force value obtained by referring to the above change table by the interruption caused by the sudden temperature change this time occurs. Amount of change (indicated by arrow)
By adding / subtracting to / from the previous servo constant (solid line), the servo constant (external force correction amount) at the current temperature indicated by the dotted line can be obtained.

After that, when a seek command is issued from the host device, the external force is corrected by the servo constant. As described above, according to the present invention, when the difference between the value obtained by holding the temperature from the temperature sensor provided in the disk device and the temperature sampled at a constant cycle is equal to or more than a predetermined ± x degrees C. When an MPU is detected, an interrupt is generated in the MPU, and the interrupted MPU re-measures the correction amount for the required external force at each cylinder position,
Re-create the servo constants or refer to the external force change table for the predetermined temperature change at the preset predetermined temperature, and detect the temperature sensor at the temperature at which this interrupt occurred. It is characterized in that the external force correction amount for the temperature difference ± x degree C is calculated, and the servo constants at the previous correction are added / subtracted for correction.

[0041]

As described in detail above, according to the present invention, the voice coil current value (digital value) for correcting the external force in a timely manner with respect to a sudden temperature change can be obtained. There is an effect that it is possible to suppress a phenomenon such as an increase in seek settling time and a seek error due to an external force correction error that occurs in a valley between corrections.

[Brief description of drawings]

FIG. 1 is a block diagram of the principle of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention (No. 1).

FIG. 3 is a diagram showing an embodiment of the present invention (part 2).

FIG. 4 is a diagram showing an embodiment of the present invention (part 3).

FIG. 5 is a diagram illustrating an external force value in a magnetic disk device.

FIG. 6 is a diagram (part 1) explaining a conventional external force correction method.

FIG. 7 is a diagram (part 2) for explaining a conventional external force correction method.

FIG. 8 is a diagram showing an example of measuring a cylinder position and an external force.

[Explanation of symbols]

1 Magnetic disk unit 11 Temperature sensor 12 Hold circuit 13 Window comparator 14 Microprocessor (MPU) 15 Head or data head 16 Voice coil motor (VCM) 17 Head arm 18 Flexible printed circuit (FPC) 100 to 106,110 to 116,120 to 123 Processing step Servo constant External force change table, change table

Claims (2)

[Claims] 1. A method for correcting an external force when a magnetic head of a disk device (1) controlled by a microprocessor (14) is moved to a predetermined cylinder position of a disk for positioning, and the disk device (1) is provided. When the difference between the value obtained by holding the temperature from the temperature sensor (11) provided therein and the temperature sampled at a constant cycle becomes equal to or more than a predetermined ± x degree, the microprocessor (14 ) Interrupted, and the interrupted microprocessor (14) re-measures the correction amount for the external force required at each cylinder position,
An external force correction method for a disk device, which is characterized by recreating a servo constant () for an external force. 2. An external force correction method for positioning by moving a magnetic head of a disk device (1) controlled by a microprocessor (14) to a predetermined cylinder position of the disk, the disk device (1) When the difference between the value obtained by holding the temperature from the temperature sensor (11) provided therein and the temperature sampled at a constant cycle becomes equal to or more than a predetermined ± x degree, the microprocessor (14 ), The interrupted microprocessor (14) refers to the external force change table () for a predetermined temperature change at each preset temperature, and generates the interrupt this time. The external force correction amount for the temperature difference ± x degrees detected by the temperature sensor (11) at different temperatures is calculated, and the servo constant () at the previous correction is added or subtracted to correct the servo constant (). De characterizing External force correction method in disk device.